Should Private Methods Be Tested?

The article focuses on discussing should private methods be tested. The following topics will be discussed here:

1. Why Do You Want To Test Private Methods?
2. Is Unit Testing Private Methods Considered A Bad Practice?
3. Reasons You Are Tempted To Write Unit Tests to Private Methods.
4. Should Private Methods Be Tested?

Let’s start discussing each of these topics in detail.

Why Do You Want To Test Private Methods?

• Private methods are typically used to encapsulate implementation details that are not intended to be part of the public API. As such, they are usually not well-documented and can be difficult to understand just by reading the code. Testing private methods can help to ensure that they are doing what they are supposed to do and are not introducing any unexpected side effects.
• Private methods can often be quite resource-intensive since they are not typically called very often. As such, it is important to ensure that they are efficient and are not wasting resources unnecessarily. Testing private methods can help to ensure that they are efficient and are not causing any performance issues.
• Private methods can often be quite complex since they typically handle a lot of the “edge cases” that are not handled by public methods. As such, it is important to ensure that they are working correctly in all cases, including those that might be difficult to test with public methods. Testing private methods can help to uncover any bugs that might be present in the implementation.
• Private methods can serve as a form of documentation for the code since the test code can act as a sort of self-documenting specification for what the method is supposed to do. This can be especially useful for complex methods that are not well-documented.
• Private methods can often be mocked, which can be useful for isolating them from other parts of the system for testing purposes. This can be especially useful for methods that interact with external services or that are otherwise difficult to test.
• Private methods can often be refactored, which can be useful for improving the design of the code or for fixing bugs. However, it is important to ensure that the refactoring does not introduce any regressions. Testing private methods can help to catch any regressions that might be introduced by the refactoring.
• Private methods can often be overridden, which can be useful for customizing the behavior of the system under test. This can be especially useful for debugging purposes.

Is Unit Testing Private Methods Considered A Bad Practice?

There is no definitive answer to this question as opinions will vary from person to person. Some people may consider unit testing private methods to be a bad practice, while others may see it as a perfectly acceptable way to test code. Unit testing private methods are considered a bad practice by some because it can lead to tightly coupled code. This means that the test code is closely linked to the implementation details of the class being tested. This can make the code difficult to change and maintain. 

There are a few reasons why unit testing private methods can be considered a bad practice:

• It can lead to tightly coupled code: The test code is closely linked to the implementation details of the class being tested. This can make the code difficult to change and maintain.
• It can be difficult to write unit tests for private methods: Private methods are usually more complex than public methods, making them more difficult to unit test.
• It can be time-consuming to write unit tests for private methods: Private methods are usually more complex than public methods, meaning that more time is required to write unit tests for them.
• Private methods can change without affecting the public interface: This means that the unit tests for private methods might not catch all the changes that need to be tested.
• Private methods can be difficult to mock: Mocking is a technique used in unit testing to simulate the behavior of dependencies. Private methods can be difficult to mock because they are not directly accessible from the unit test code.

Overall, unit testing private methods can be considered bad practice because it can lead to tightly coupled code, it can be difficult to write unit tests for private methods, and it can be time-consuming to write unit tests for private methods.

Reasons You Are Tempted To Write Unit Tests to Private Methods

1. Increase Code Coverage: One of the main reasons why you might be tempted to write unit tests for private methods is to increase your code coverage. By testing private methods, you can be sure that your code is fully covered and that all possible scenarios are being taken into account. Achieving a high level of code coverage is a good practice in software development. It helps to ensure that the code is working as expected and that there are no hidden bugs. By writing unit tests for private methods, we can increase the code coverage of our application. 
2. Every Method Needs Its Test Case: Another reason why you might want to write unit tests for private methods is that every method needs its test case. This is especially true for private methods that contain a lot of logic. By writing a unit test for each private method, you can be sure that all the logic is being tested and that there are no gaps in your coverage. 
   Every method needs its test case. This is especially true for private methods. Private methods often contain a lot of logic that needs to be tested thoroughly. By writing a unit test for each private method, we can ensure that all the logic is covered. 
3. There Is A Lot Of Logic In Private Methods That Needs Special Attention: Finally, another reason why you might be tempted to write unit tests for private methods is that there is a lot of logic in private methods that need special attention. Private methods often contain complex logic that needs to be thoroughly tested. By writing unit tests for these methods, you can be sure that the logic is being tested properly and that there are no errors. There is a lot of logic in private methods that need special attention. Private methods often contain complex logic that needs to be tested thoroughly. By writing unit tests for private methods, we can ensure that all the logic is covered and that there are no hidden bugs.

Should Private Methods Be Tested?

There is no simple answer to the question of whether private methods should be tested. The answer depends on several factors, including the nature of the method, the purpose of the test, and the testing methodology being used. 

• In general, private methods should only be tested if there is a reason to believe that they are not working correctly. For example, if a private method is critical to the functionality of the class, or if it is called by a public method that is being tested, then it may be necessary to test the private method.
• If the purpose of the test is to verify the functionality of the class as a whole, then it may not be necessary to test private methods. However, if the purpose of the test is to find bugs in the implementation of the class, then testing private methods may be necessary. The testing methodology being used can also influence the decision of whether to test private methods. For example, if unit testing is being used, then it is generally recommended to test private methods. However, if integration testing is being used, then private methods may not need to be tested. 
• Unit tests are important because they allow developers to test their code independently. However, some developers make the mistake of assuming that every method needs its test case. In reality, a test case for each public method that activates multiple methods within the code is usually sufficient. Additionally, some developers believe that there is a lot of logic in private methods that need special attention. But, it is usually best to refactor your code instead of trying to write complex test cases.
• Assuming that every method needs its test case is a common mistake made by developers who are new to writing unit tests. This is because they misunderstand the concept of unit testing and instead think of it as testing pieces of code independently. However, with more practice, it is possible to improve one’s unit testing skills by writing test cases for public methods that activate multiple methods within the code.
• There is often a lot of logic present in private methods that need special attention when writing test cases. This is because if there is a lot of logic present in a method, it becomes more complex to write tests that cover all of the logic. However, it is important to keep in mind that if a method is too complex, it is likely that the code itself is too complex and could benefit from refactoring. Therefore, the problem might not be that the private method is difficult to test, but that the code is too complex. If the complex code is in private methods, this can increase the complexity of writing good tests.

Ultimately, the decision of whether to test private methods should be made on a case-by-case basis. No hard and fast rule says private methods must always be tested, or that they should never be tested. The decision should be based on the specific situation and the goals of the test.